Circuitry for processing data packets within a data networking environment is generally composed of a plurality of data processing blocks that perform specific calculations necessary for processing the data packets in a desired manner. The data processing blocks are often connected in a sequence wherein an input data packet is processed and passed to each subsequent data processing blocks such that processed data packets are propagated through the sequence of data processing blocks.
Data are organized in packets of successive data of fixed or variable size. A data packet is made up of one or more data blocks. Each processing block can process a packet of data in different ways, but all the data are processed the same way within a packet. A set of configuration parameters is applied to each block by a central controller that indicates what kind of processing is to be performed on the packet of data. As the configuration parameter must remain the same for any data block during the processing of a packet, the configuration parameters can only change on the packet boundaries.
The data processing blocks may be reconfigured by applying different configuration parameters in the blocks to adjust the calculations performed within the blocks. This is useful, for example, in a data networking environment using different standards wherein the processing of the data packets must be adjusted in accordance with the standard used.
Also, in a system having a plurality of data processing blocks, it is possible to use a handshaking method of transferring data between the data processing blocks. In such a scheme, each of the data processing blocks are able to provide and receive a ready to send (RTS) signal, which signifies that the block is ready to send a data block, and a ready to receive (RTR) signal, which signifies that the block is ready to receive a data block. A data transfer is performed synchronously between two data processing blocks when the both signals are present, that is, the sender provides a RTS signal and the receiver sends a RTR signal, on the rising edge of the clock.
In a system that utilizes a chain of data processing blocks that receives configuration parameters from a controller to determine what kind of processing is to be performed on the data packets, and also utilizes the handshaking scheme for exchanging data packets, a problem may exist in ensuring that the proper configuration parameters are being utilized by the data processing blocks. In this regard, it may be the case that the number of input bytes is not necessarily the same as the number of output bytes. Since the handshaking scheme is used to exchange the data packets, the time when the first data of a packet is processed by a particular data processing block may vary. The time may be different for each block because the arrival of the first data block of the data packet may not be the same for all. It depends on whether the block is ready to process data, and whether the preceding block is ready to pass data. In this environment, the controller, which provides the configuration parameters for the blocks, does not know when each block receives the first data block of the data packet and needs to have the configuration parameters updated. Therefore, it is desirable to provide a system that ensures that the configuration parameters are updated in the data processing blocks at the proper time to overcome the above.